The present invention relates to a set of iron-type golf clubs, more particular to a set of iron-type golf club heads in which the moment of inertia around a horizontal axis parallel to the toe-heel direction is peculiarly defined in relation to the mass of the head to improve the stability of flight distances of golf balls.
In recent years, it has been proposed to lower the center of gravity of a golf club head in order to make it easy to hit a golf ball on the upper side of a sweet spot of a club face and thereby to provide a great vertical gear effect for the hit golf ball. As a result, the amount of back spin given to the hit golf ball becomes decreased. Thus it is prevented to hit the ball high in the sky due to the back spin, and the flight distance of the golf ball can be improved.
Meanwhile, in the case of a club head having a great loft angle, ball hitting positions are apt to be varied widely in the club face toward the upper side or lower side of the sweet spot. Therefore, the amount of back spin of the hit golf ball is varied wide, which disadvantageously causes unstable flight distances.